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A THESIS Presented to the Faculty of The Graduate College at the University of Nebraska In Partial Fulfillment of Requirements For the Degree of Master of Science, Major: Animal Science, Under the Supervision of Professor Galen E. Erickson. Lincoln, Nebraska: December, 2015

Copyright (c) 2015 Bradley M. Boyd

Abstract

Trial one was conducted at the United States Meat Animal Research Center (MARC) near clay center, NE during the summer of 2014. The objective of this trial was to measure the effects of supplementing zilpaterol hydrochloride (ZH) for the final 21 days of the finishing period, and shade, on performance, body temperature, respiration rate, and mobility of finishing beef steers. Feeding ZH increased hot carcass weight, dressing percent, longissimus muscle area, and reduce USDA yield grade. Shade did not affect steer performance and did not reduce body temperature. Zilpaterol hydrochloride increased respiration rate when compared to control cattle and had minimal effect on animal mobility. Zilpaterol hydrochloride and shade had little effect on steer body temperature.

Trial 2 and 3 were conducted during the summer and fall/winter of 2014 at the University of Nebraska-Lincoln (UNL) Agricultural Research and Development Center (ARDC) near mead, NE. The objective of these trials was to assess the effects of environmental conditions on body temperature and blood metabolites across season on finishing steers. Body temperature was correlated to environmental temperature during both trials however the correlations weren’t as strong for the winter trial. Many blood metabolites were correlated to environmental and rumen temperatures suggesting that blood metabolites are affected by environmental conditions.

Trial 4 was conducted at UNL ARDC with the objective to determine the effect of feeding Agrimos (Lallemand Animal Nutrition; Montreal, Canada) and 2.5-cm ground wheat straw to finishing steers, during the summer, on body temperature and panting score in addition to performance, and blood metabolites. Hot carcass weight, dressing percent, LM area, and marbling score were not different between treatments. The addition of Agrimos (Lallemand Animal Nutrition; Montreal, Canada) increased steer body temperature with no impact on steer performance. The addition of finely ground wheat straw decreased steer panting score and reduced feed efficiency over both the control and Agrimos fed cattle. Control cattle had greater 12th rib fat depth and as a result USDA yield grade.